Major technologic advances in genomics have made possible the identification of critical genetic alterations in cancer, which has led to a rapid paradigm shift in what is now considered personalized cancer treatment. This exponential growth in the understanding of cancer genomics is reshaping the drug development process, from drug discovery to novel designs of clinical trials. It is also exposing the critical importance of rigorous validation of molecular diagnostics platforms, such as the use of whole-exome sequencing and patient-derived xenografts, which may eventually be utilized to guide treatment decisions and may ultimately enable the true practice of personalized oncology. This review describes the achievements in therapeutic and molecular diagnostics, details evolving molecular platforms, and highlights the challenges for the translation of these developments to daily clinical practice.